A thriller with an agenda, Emma Healey's Elizabeth is Missing is the most entertaining of these four books, summarized below.

Why Dementia Is A Common Theme

Nina Silverberg, assistant director of the Alzheimer's Disease Centers Program at the National Institute on Aging, says dementia is more prominent in literature because it's more prominent in life. "Alzheimer's is becoming a more common theme because it simply affects more people and more family members, and that includes novelists,” Silverberg says.

In fact, it includes at least three of the four above-mentioned novelists. The father of the author of We Are Not Ourselves, Matthew Thomas, was diagnosed with early-onset Alzheimer's, as was the father character in his book. The grandmothers of Healey and Lisa Genova, who wrote Still Alice, suffered from cognitive disorders.

"My grandmother gave me the trigger for the book when she was in the car with me and my dad one day and she said, 'My friend is missing.' I thought that was interesting and scary," says Healey.

"We knew this friend wasn't missing but I thought, 'What if she really had been? What if this were something my grandmother couldn't retain, so she kept forgetting it over and over?' At the time, her dementia was in quite early stages, but I kept thinking about the idea for the next year, as her dementia got much worse," she adds.

A Twist on the Unreliable Narrator

Healey’s story has been a hit in her native England and in the U.S. The book provides a unique window into dementia because it takes place entirely in Maud's (the grandmother character) head.

Much like The Curious Case of the Dog in the Night-Time, whose narrator had a form of Asperger syndrome, Elizabeth is Missing centers on a mystery that might be easily solved by some people but that comes to obsess the narrator, who cannot grasp all of the facts in front of her.

Unlike, say, Lolita, where the unreliable narrator is someone we cannot trust, the narrators in Elizabeth and Curious Case are unreliable because they cannot trust their own brains.

"It's a horrible thing to say, but dementia is a great gift to a novelist," says Healey. "There's a kind of de-familiarization that it causes, so you are able to write about ordinary things from a totally new perspective. I was dying to find a way to explain things, to figure out what was going on in my grandmother's head, and I thought fiction might be a way in."

Where Truth Meets Fiction

In many ways, the novels depict reality, with details that ring true.

For instance, in We Are Not Ourselves and Still Alice (the movie version is now out and Julianne Moore, who plays the title role, just won the Golden Globes Best Actress award for her performance and has been nominated for an Oscar), the characters with Alzheimer's are 50-ish professors, highly-functioning individuals who delay treatment during crucial years because they are so good at hiding and compensating for their symptoms.

"Different people are more resilient, especially people with higher levels of education, so it's realistic that some people are able to hide it better," says Silverberg. "It's also the case that some people are unaware of a decline, because we used to think that people who got older slowly lose their memories. They think that's normal and, even if they do suspect it's Alzheimer's, they frequently deny it, whether to themselves or others."

Other details that pop up across the four novels — the strain on loved ones, worry over passing on genes related to Alzheimer's, the frustration of writing Post-It note reminders to oneself, only to forget what the notes refer to — also sound familiar to Silverberg.

Although she likes to keep abreast of what pop culture is saying about Alzheimer's, Silverberg has not read any of these four books because she's not looking for sadness in her recreational reading. But based on what she has heard, she believes the books can offer hope by documenting how far we've come in understanding and treating cognitive disorders.

"Sometimes, physicians haven't wanted to give a diagnosis because there's nothing that can magically cure it, but this is the message we want to get out: We do understand certain behaviors and there are lots of thing to do if people at least understand what's going on," says Silverberg.

"I hope (these books) will help raise awareness and especially encourage people to participate in research so we can find a way to gain a better understanding of the disease."

Summaries of 4 Dementia-Themed Novels

Elizabeth is Missing, by Emma Healey — Strong-willed Maud searches for her best friend, whom she believes may have been the victim of foul play, while she, her family and her caregivers cope with her worsening symptoms of dementia.

Still Alice, by Lisa Genova — Over the course of about a year, the novel charts the course of a Harvard professor's memory loss. With its information on genetic markers, support groups and early testing, it’s almost like an instruction manual in the guise of a novel.

A Sudden Light, by Garth Stein — A man and his teenage son return to the crumbling mansion where the father grew up. They grapple with the family patriarch's Alzheimer's and the ghosts that haunt the place.

We Are Not Ourselves, by Matthew Thomas — Simultaneously mammoth and intimate, Thomas' saga charts the fortunes of Ed and Eileen Leary (and their son, Connell) over a span of five decades. It’s a tough read, but the best-written of the four.

Chris Hewitt is a movie and theater critic who has written for MSNBC.com, Today.com and The History Channel magazine and whose reviews have run in newspapers across the country.